An extremely rare treefern found only in a few sheltered gullies in
Tasmania, Victoria, and New South Wales. It is now generally believed
that they are of hybrid origin, probably resulting from a cross between
Cyathea australis and Cyathea cunninghamii. It is very
fast-growing, large, and very distinctive; a fern of deep ravines and streambanks.
The trunk may grow to a height of 30' tall and over 16" thick, with fronds
sometimes exceeding 12' in length. It certainly has the potential
for great ornamental worth in cold climates. Unlike C. cunninghamii,
the dead fronds tend to persist around the trunk forming a skirt.

Only a small population of about 40 plants occurs in Tasmania, but Victoria
has some larger populations. As all attempts to raise this fern from
spore have failed, it probably does not produce fertile spore as a hybrid.
However it has been theorized that plants can be obtained by sowing a small
amount of Cyathea australis spore with a large amount of C. cunninghamii
spore, saving a large proportion of the offspring and picking out the hybrids
as they develop. So unfortunately it may be a while before temparate
gardeners will be able to test these out. It will almost certainly
be hardy to 20°F or lower, and could make a spectacular addition to
a cool zone 7 or 8 garden with some protection.